Provider scenario tests (#3688)

Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose/src/agents/agent.rs

@@ -63,7 +63,7 @@ const DEFAULT_MAX_TURNS: u32 = 1000;
 /// The main goose Agent
 pub struct Agent {
     pub(super) provider: Mutex<Option<Arc<dyn Provider>>>,
-    pub(super) extension_manager: Arc<RwLock<ExtensionManager>>,
+    pub extension_manager: Arc<RwLock<ExtensionManager>>,
     pub(super) sub_recipe_manager: Mutex<SubRecipeManager>,
     pub(super) tasks_manager: TasksManager,
     pub(super) final_output_tool: Arc<Mutex<Option<FinalOutputTool>>>,

crates/goose/src/agents/extension_manager.rs

@@ -338,12 +338,16 @@ impl ExtensionManager {
                 .insert(sanitized_name.clone());
         }
 
-        self.clients
-            .insert(sanitized_name.clone(), Arc::new(Mutex::new(client)));
-
+        self.add_client(sanitized_name, client);
         Ok(())
     }
 
+    pub fn add_client(&mut self, client_name: String, client: Box<dyn McpClientTrait>) {
+        let sanitized_name = normalize(client_name);
+        self.clients
+            .insert(sanitized_name, Arc::new(Mutex::new(client)));
+    }
+
     /// Get extensions info
     pub async fn get_extensions_info(&self) -> Vec<ExtensionInfo> {
         self.clients

crates/goose/src/agents/reply_parts.rs

@@ -34,9 +34,7 @@ async fn toolshim_postprocess(
 
 impl Agent {
     /// Prepares tools and system prompt for a provider request
-    pub(crate) async fn prepare_tools_and_prompt(
-        &self,
-    ) -> anyhow::Result<(Vec<Tool>, Vec<Tool>, String)> {
+    pub async fn prepare_tools_and_prompt(&self) -> anyhow::Result<(Vec<Tool>, Vec<Tool>, String)> {
         // Get tool selection strategy from config
         let config = Config::global();
         let router_tool_selection_strategy = config